Digital assistants have been made by several prominent technology firms. For example, Microsoft Corp. has Cortana™ Apple Corp. has Siri™ Amazon Corp. has Alexa™ While Google Corp. has Google Home. Some assistants currently run only on smartphones, while others also run on dedicated hardware. For example, Alexa runs on the Amazon devices Echo and Tap. Amazon sold 8 million Echoes in 2016. The Echo is the most common digital assistant to date.
Typically the devices are installed in a user's home. They usually lack a screen. A device might output sound and accept as input spoken commands from the user. The device is connected by wired or wireless means to a computer network (often the Internet), and through this network, to a server.